Decay ofK42andSc44

Abstract

The low excited states of ${\mathrm{Ca}}^{42}$ and ${\mathrm{Ca}}^{44}$ have been studied in the decay of ${\mathrm{K}}^{42}$ and ${\mathrm{Sc}}^{44}$, with special emphasis on the observation of weakly populated states. In the ${\mathrm{K}}^{42}$ decay, gamma rays have been seen at 0.31 Mev (1.1%), 0.49 Mev (<0.1%), 0.60 Mev (0.1%), 0.90 Mev (0.1%), 1.02 Mev (0.1%), 1.52 Mev (100%), 1.92 Mev (0.3%), and 2.42 Mev (0.2%). The coincidence sequence of the transitions has been measured and a level scheme constructed. In the ${\mathrm{Sc}}^{44}$ decay, gamma rays have been seen with energies and intensities of 0.68 Mev (3.2%), 1.02 Mev (3.1%), 1.12 Mev (4.7%), 1.16 Mev (100%), 1.50 Mev (1.7%), 1.72 Mev (0.8%), 2.28 Mev (0.2%), and 2.69 Mev (0.2%). Coincidence measurements were also taken for this isotope to clarify the cascade sequences, and a level scheme was constructed. A search was made for low-energy conversion electrons ($E<\mathrm{}1\mathrm{}$ Mev) in an effort to establish the existence or nonexistence of a low-lying $0^{+}$ state in ${\mathrm{Ca}}^{44}$, whose analog occurs as the second excited 1.84-Mev state in ${\mathrm{Ca}}^{42}$. No such conversion electrons were seen, by either electron spectrometer studies or by electron-delayed gamma-ray coincidence measurements. An upper limit of 0.05% of the total decay of ${\mathrm{Sc}}^{44}$ was put on the population of such a state.